[Effect of pneumoperitoneum on ultrastructure of parietal peritoneum in experimentally induced peritonitis in the...

Aim of this study was to analyse the effect of gastric perforation induced peritonitis and a pneumoperitoneum (PP) on the ultrastructure of the parietal peritoneum. After randomisation rats allocated to groups I and II were subjected to standardized gastrotomy simulating gastric perforation. After a 12-h-interval a PP was induced in groups I and III. After PP for 60 min a primary fixant was injected intraperitoneally as the abdominal wall was still extended, as well as 30 s, 2 h and 12 h after release of the PP. In groups II and IV simple puncture of the abdomen was performed. Animals were sacrified and tissue specimens taken from the parietal peritoneum of the left diaphragm were analysed using raster electronic miroscopy (REM: 100x to 5000x). In group II (gastric perforation without PP) microvilli appeared shrunk and coarse, while integrity of the mesothelial cell layer remained intact up to 2 h after abdominal puncture. In group I (gastric perforation with PP) distortion of the mesothelial cell layer with concomittant opening of stomata to the submesothelial tissue was observed already in specimens harvested as the abdominal wall was still extended. Concomittantly scarce microvilli appearing coarse and thickened were laid flat on top of the mesothelial cells. After desufflation a rapid process of mesothelial desintegration with disruption from the submesothelial layer and vanishing of microvilli occurred. In REM analysis of parietal peritoneum premature distortion and desintegration of the mesothelial cell layer was observed after exposure to increased abdominal pressure and to gastric perforation-induced peritonitis.